Can the polygraph test really spot a lie?

From dating shows to police interrogation rooms, the polygraph test has long been marketed as a way to detect deception. But can it really? And who decided we needed a truth machine in the first place? In this episode, a Throughline listener sends us on a quest to uncover the story of the lie detector. Guests: Ken Alder, professor of history at Northwestern University and author of The Lie Detectors: The History of an American Obsession Support public media with NPR+ and enjoy perks for over 25 podcasts like this one. This show’s perks include sponsor-free listening. Learn more at plus.npr.org http://plus.npr.org/. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

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• 0:20Speaker 01

  It's springtime in Berkeley, California, 1921. A group of college-aged women are whispering to one another in the halls of their dormitory. A man named John Larson arrives on campus carrying his brand-new invention, the cardio pneumo psychograph, an early version of a polygraph machine.

• 0:43Speaker 02

  And there's been pelfering in the sorority, including a diamond ring's gone missing and a bunch of other stuff. And Larson is asked to solve the crime after, you know, the old-school police guys just can't do it. They just started asking these women. They realize it's an inside job, but they don't know who did it.

• 1:00Speaker 01

  Larson is a trained physiologist who just joined the police force. This is the lie detector's first trial run. One after another, he asks these women questions. And when he gets to suspect number 14, she seems nervous.

• 1:16Speaker 02

  And when he asks her whether she stole the diamond ring, she gets furious, pulls off the apparatus and runs out of the room. And then over the next few days, the police sort of follow her and hound her. And eventually, she confesses to the court.

• 1:30Speaker 01

  The lie detector had solved its first case, or so it seemed.

• 1:35Speaker 02

  Did she really do it? Larson had doubts later whether or not she is in fact guilty. And the crimes continued. And she clearly had psychological issues. She herself admitted to this. And so the psychological effect of lie detectors is to make people feel incredibly guilty. And they do confess to things. Whether those confessions are true is then a different question, right?

• 1:58Speaker 01

  This is through line from NPR. I'm your host, Rund Abdelfatah. We got an email from a listener named Frankie, who said they were asked to take a polygraph test as part of the hiring process for a job working for Orange County in Florida. Frankie had the impression that these tests were pseudoscience and can't actually detect when someone is telling a lie. Frankie wanted to know, what's the backstory of these tests? And if they're junk science, why are they still used in the workplace?

• 2:29Speaker 02

  You know, it's always fascinated me that there's this device that claims to tell the truth. And it's a story of science that that would be possible always intrigued me.

• 2:38Speaker 01

  This is Ken Alder. He's a professor of history at Northwestern University. He's also the author of The Lie Detector: The History of an American Obsession. And it is an American obsession.

• 2:52Speaker 03

  We have the results of the lie detector right here.

• 2:57Speaker 01

  The polygraph may be most familiar to us in the context of daytime TV. Think The Maury Show.

• 3:03Speaker 03

  During your relationship with destiny, have you ever had sexual intercourse with any other women? You said no. The lie detector determined that was a lie more than five women.

• 3:12Speaker 01

  The lie detector is also used in police investigations.

• 3:15Speaker 04

  Police wanted a confession. Duxbury agreed to take a polygraph test that experts say he failed.

• 3:23Speaker 01

  The National Academy of Sciences and the Office of Technology Assessment under Congress have both conducted studies on the effectiveness of the lie detector test.

• 3:32Speaker 02

  And time and time again, come to the conclusion that it's at best ineffective and quite possibly infrequently counterproductive.

• 3:42Speaker 01

  And yet, we just can't seem to quit it.

• 3:45Speaker 05

  Some federal agencies are ramping up efforts to identify leakers. That includes the FBI, which, in recent weeks, has been using polygraphs. That's right, the so-called lie detector test.

• 3:57Speaker 01

  When we come back, Ken Alder explains why we got the polygraph test in the first place and why you still might encounter it in the workplace.

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• 5:58Speaker 07

  I'm Chief Warrant Officer Foster. And I would like, in this film, to show you a reenactment of how I made use of the polygraph during the investigation of a crime a few months ago.

• 6:10Speaker 01

  For a device that claims to detect something as slippery and complicated as a lie, the polygraph machine is actually surprisingly simple. It measures your heartbeat, blood pressure, your breathing depth, and how sweaty you are.

• 6:24Speaker 07

  Bear in mind that the polygraph is not a substitute for a thorough investigation. It is an investigation aid.

• 6:31Speaker 01

  It basically measures your body as an emotional instrument, all while being asked a series of questions.

• 6:38Speaker 07

  The subject's attention must be concentrated on the questions he has asked. The polygraph may have a psychological influence on a subject. To many, it is an unknown quantity, and of such, may be feared.

• 6:51Speaker 01

  The real complexity or trick to the polygraph, as Ken explains, happens in the design of the questions.

• 6:59Speaker 02

  The machine itself is a bit of what magicians call a misdirect. You're all focused on the machine, but it's actually the questions and the rituals and the penumbra, all the things that are going on around it, which make the polygraph "successful" in quote marks.

• 7:16Speaker 07

  Now, Danny, I want you to answer each question with a yes or no, or no more.

• 7:22Speaker 02

  The usual, original way to use a lie detector is to ask people questions that are relatively innocuous.

• 7:27Speaker 07

  Is your last name Armstrong? Yes. Were you born in the state of Missouri? Yes. Do you sometimes watch television? Yes.

• 7:38Speaker 02

  And, you know, people presumably answer truthfully, and they're not stressed. And then you ask them--

• 7:43Speaker 07

  Did you steal that watch? I told you I didn't. Now, Danny, please. I asked you, answer each question yes or no.

• 7:51Speaker 02

  And their body reacts. So that's relevant and irrelevant questions. But there are other techniques, too, for, you know, designing the interrogation that are meant to bring out guilt or physiological reaction in any case. For example, let's say the police know the amount that was stolen, and it's not been written up in the papers. And let's say it was $1,000. You ask the suspect, was it $800? Was it $1,000? Was it $1,200? And you look at the differential reaction to gauge whether or not they're telling the truth.

• 8:22Speaker 01

  Right. That's a little more precise than, you know, because if someone asked me, like, did you murder this person last Thursday, I might freak out internally, even if I didn't do it. You know what I mean? Because I'd be like, oh, god, they think I murdered this person last Thursday, you know?

• 8:34Speaker 02

  No kidding. And it's a police interrogation. I mean--

• 8:37Speaker 07

  Maybe the machine is wrong.

• 8:40Speaker 07

  No, there's nothing wrong with the instrument.

• 8:45Speaker 01

  Well, let's go back to the early days of the polygraph test. Can you set the stage for how it comes into existence? Who invents it and why?

• 8:55Speaker 02

  Yeah, so it's invented Berkeley, California, my hometown. And it's invented in the 1920s, in the early 1920s, because the leader of the police force there is a guy named August Volmer, probably the most important police officer in the history of the United States. And he's the police chief of Berkeley, but he wants to reform the police. This is 1920. The police have a reputation for being themselves pretty not law-abiding, to put it politely.

• 9:20Speaker 01

  This is like the height of like bootlegging prohibition era.

• 9:25Speaker 02

  Exactly. And frankly, police were known then especially, and maybe even to this day, for using very violent methods for getting evidence from people.

• 9:36Speaker 01

  Police chief Volmer really wanted to change the police force to be more humane, less violent. And so he linked up with a PhD student at Berkeley, who was a physiologist, John Larson, the guy who tested the lie detector on the women from the sorority. Together, Volmer and Larson developed this new technology.

• 9:57Speaker 02

  The theory being that it was better than violence. And the idea was to make the police themselves, you know, more law-abiding. And frankly, the first people it's used on are the police themselves. The first people to be systematically subjected to lie detector tests are the Berkeley police.

• 10:15Speaker 01

  August Volmer is often called the father of modern policing. And one of his focuses was increasing professionalism within the police department. Subjecting police officers to the lie detector was a part of that vision. He wanted to make sure they themselves were not committing crimes to increase trust in the new technology and create an aura of truthfulness, real police reform.

• 10:41Speaker 02

  So, I mean, in a way, the use of the lie detector in employment begins at the very beginning.

• 10:46Speaker 01

  Wow. So was there any backlash? Or was there any skepticism about this new invention that was really fundamentally changing how police work was done?

• 10:59Speaker 02

  Yeah, there's pushback from two directions. One is from within, in the law, where judges proved incredibly reluctant to let juries hear lie detector evidence, lest it become, in a way, the queen of all proofs, right? I mean, if you have a lie detector and it works 100%, why do you need a jury at all? You know, you could just use the machine. In fact, in a very, very famous court decision, a case named the US versus Frye, there was a murder committed in DC. And on the basis of a confession in part, but then a retracted confession, a lie detector is brought in and it exonerates the man. But the judge refuses to let the jury hear the lie detector exoneration evidence.

• 11:44Speaker 02

  And that goes all the way up to the second highest court in the land, and what's called the Frye ruling, basically says, we will only let into the courtroom that scientific evidence which passes muster with the scientists themselves. We will defer to the experts. We will be, as it were, sociologists of science.

• 12:06Speaker 01

  But the polygraph could still be used in other settings, like in police interrogations. And some people were really uncomfortable with the way it was being used.

• 12:16Speaker 02

  The other place resistance was very vocal was in the lie detector operators themselves, including Larson, who really was horrified by how the lie detector was being used to basically psychologically coerce people to confess. One important thing to remember, of course, is the police can lie to you in a police interrogation, right? They're not bound to tell you the truth. So they often will accuse people of crimes they didn't commit knowingly to see what kind of reaction they have. And then if they say anything that incubates them, then yeah, that's admissible in court, even if the lie detector tests itself is not.

• 12:55Speaker 01

  But how does that make sense? If it's deemed not scientific enough in the courtroom, why is it scientific enough in the interrogation room?

• 13:03Speaker 02

  Because confessions are willfully given and appropriate police work requires confirming and corroborating confessions. Police get many confessions for crimes. Then the question is, do you corroborate that? But it's a legitimate lead and possible indication of guilt.

• 13:24Speaker 01

  So by now, you might be asking the same question our listener Frankie asked us, which is, how does the lie detector start becoming used in the professional workplace beyond the police? Well, it turns out Larson had a former coworker named Leonard Keeler, who brought the polygraph to Chicago in the 1930s.

• 13:43Speaker 02

  And what's the, basically, the first scientific crime lab in the United States, scientific crime detection lab.

• 13:50Speaker 02

  And in that capacity, he's looking in part to raise private revenue. And he starts to go around to banks and other local employers, like Walgreens, and offer them his service, polygraphing their employees. And what he discovers, when they let him do it at banks, for example, is that people will confess to having taken petty cash or having, in other ways, violated the company's rules. And the managers who brought Keeler in to do these tests are shocked, horrified, and want to fire these employees. And Keeler says, don't do that. Bring me back. And these will become the most honest employees you will ever have, because they will know that they're constantly being surveyed.

• 14:34Speaker 02

  And in fact, that's what begins to happen. So polygraphs begin to spread in the commercial sector as a way to monitor people over time. And it's used in, you know, banks and in all kinds of retail. And eventually, the US government begins to use it for employees as well.

• 14:52Speaker 01

  So it's like the OG surveillance system.

• 14:54Speaker 02

  Exactly. And it's an inside-out. It's like a light shining, not just on your exterior, but on your inner self, as it were. Because the idea is it's monitoring your thoughts, the things you don't speak, the things you're trying to hide and conceal within you, within your conscience, as it were. And so it becomes a very effective tool of that kind of policing, psychological policing.

• 15:17Speaker 01

  Right. I mean, policing is the right word for it, right? I mean, this is literally a police tool that's suddenly being used across society in civil life. If it wasn't on the radar of people beforehand, for the average person in the country who suddenly is going to apply for a job or is in a job that suddenly is adopting the lie detector test, that's a pretty big change for you as an employee.

• 15:40Speaker 02

  Absolutely. And employers at that time were within their rights to fire people for being unwilling to take the test. Certainly, they don't have to hire people that they think have done poorly on the test. And it's used also in the federal government at Los Alamos and at what's called Oak Ridge, Tennessee, where the uranium is built to protect the secrets of the atomic bomb. The idea being, these are people whose secrets must not leak.

• 16:07Speaker 01

  I can understand it in that context.

• 16:08Speaker 02

  You do, aha.

• 16:09Speaker 01

  You know?

• 16:10Speaker 02

  Well, the problem with doing it on thousands of people and surveying it this way is that even if your lie detector is very accurate, which it is not, you're still generating huge numbers of false positives, huge numbers of false positives, all of whom you have to then investigate. And the false negatives are skating by.

• 16:29Speaker 01

  Right.

• 16:29Speaker 02

  So in fact, you're actually making things worse. It's a terrible tool. The math is terrible.

• 16:38Speaker 01

  From the 1930s on, the polygraph was used in both private and public workplaces. But eventually, things shifted as more and more people doubted its ability to improve conditions. Over the years, especially in the 1960s, pressure came from labor unions and ordinary citizens who felt their rights were being violated and too many people were being falsely accused. States began to pass laws banning the use of lie detectors in employment situations.

• 17:06Speaker 02

  And I think about half the states by the 80s had banned it. It was still allowed by federal law. And then Reagan, who was president at the time in the 80s, had really wanted to use it to pursue leaks in his administration. But his secretary of state, a man named George Shultz, he hated them. He thought they were scientifically useless and counterproductive. And he threatened to resign if these continued.

• 17:30Speaker 01

  And that was enough to galvanize Congress and then Reagan himself to make a change. In 1988, President Reagan signed the Employee Polygraph Protection Act, which essentially banned polygraph testing on private sector employees.

• 17:45Speaker 02

  Now, there were some carve-outs. One is that governments, especially governments that look after state secrets, like the Manhattan Project or like national security, were allowed to continue using it. So that continues. Police officers continued to be subjected to polygraphs and certain other exceptions, like the pharmaceutical industry, for some reason, is allowed. But it's greatly diminished. From a peak of 2 million tests per year, it's down to a much smaller number now. But it's still true that in the Department of Energy and other places, people would subject it to lie detectors.

• 18:27Speaker 01

  So, given that, over the course of the 20th century, you have this proliferation of the lie detector test through American life. And then there's a kind of scaling back with this 1988 act. Is this confined to the US? Or does the lie detector begin to transcend borders and travel?

• 18:47Speaker 02

  It does eventually and in limited ways. But it's basically an American story. And I think it's American in the same way that the SAT is American. So, the SAT test seems on its surface to be machine-like, right? It's neutral. It can be graded by a machine. It's being assessed by a machine. And in that sense, it seems to have the property of treating everybody the same, a kind of equality. Now, people have criticized SAT scores and SATs as, in fact, embedding presumptions and, if you like, prejudices within the test. And certainly, the same is true for the lie detector, where the discretion of the operator is the one that decides it.

• 19:31Speaker 01

  Hmm.

• 19:32Speaker 02

  That's a very American belief, that there's a neutral way to solve social problems like that.

• 19:38Speaker 01

  Throughout this conversation, it occurred to me that the problem with the polygraph might be more than just its inability to detect a lie from the truth, that it creates an illusion of security that might actually make things more insecure.

• 19:53Speaker 02

  It's called security theater, and it's a very powerful tool. You could argue that, you know, every time we go through the metal detectors at the airport, there's a bit of this kind of security theater going. And it gives you a false sense of security, absolutely. And yet, we keep using it. And so, the basic problem remains. As Montaigne said 450 years ago, "The truth has one face, but the liar has many, many thousands." And it's a very tricky game to try to ferret out what's going on in somebody else's head. And maybe, maybe we should put our efforts all to work.

• 20:33Speaker 01

  Thank you to Ken Alder. To learn more about the fascinating history of the polygraph test, you can read his book, "The Lie Detectives: The History of an American Obsession." And thanks so much to our listener Frankie for their question, which inspired this episode.

• 20:53Speaker 01

  That's it for today's show. Throughline was created by me and Ramtin Arablouei. This episode was produced by me and... Skylar Swenson. Jasmine Romero. Sarah Wyman. Julia Redpath. Amy Padula. Leanna Semstrom. Molly Marcello. Irene Noguchi. This episode was fact-checked by Sarah Knight and mixed by Robert Rodriguez. Music by Ramtin Arablouei and his band, Drop Electric. Thanks also to Johannes Dergi. I'm Rend Abdelfattah. Thanks for listening.

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